1. Field of the Invention
The present invention relates to an apparatus system for alignment of machine shafts; in particular it applies to alignment of horizontal coupled machine shafts.
Such shafts, when in perfect alignment, will have their extended center lines coincide along the same straight line (or curve in the case of long slender shafts) in space. Perfect alignment seldom occurs, but good alignment should be attained for any machine needing continuous, reliable operation. Poor alignment can cause excessive vibration and premature failure of bearings, seals, couplings, rotating elements, stationary machine structure and connected piping and duct work.
The apparatus of the present invention is specifically related to "cold" alignment, although thermal growth or "hot" alignment may be accounted for in some measure by calculation, provided that the information on the thermal characteristics of the aligned components is known. In any event, "hot" alignment is not the subject matter of the present invention and other specific apparatus will best serve that purpose.
The alignment task can be divided into three main phases: (1) measurement (the subject matter of the present invention), (2) calculation (the present inventor's U.S. Pat. No. 3,789,507) and (3) movement (the present inventor's U.S. Pat. No. 3,849,857). It is readily apparent that the latter two steps depend on the accuracy of the measurement.
The two most commonly employed methods of determining misalignment are the "face and rim" method and the "reverse indicator" method, both of which normally employ dial indicators for measurement. The present apparatus will work equally well for both methods and is especially useful for the reverse indicator method which is the most accurate in most circumstances.